Device and method for pulling pipe

ABSTRACT

A pipe puller system and methods of pipe extraction are shown. In one example a pipe to be replaced is pulled by attaching a pulling force to multiple locations along a length of the pipe. In one example pulling forces can be varied between different attachment locations to better control or eliminate tearing of the pipe. In one example, a pipe loosening device may be used prior to pulling the pipe from the ground.

CLAIM OF PRIORITY

This patent application claims the benefit of priority, under 35 U.S.C.§ 119(e), to U.S. Provisional Patent Application Ser. No. 62/661,177,entitled “DEVICE AND METHOD FOR PULLING PIPE,” filed on Apr. 24, 2018,which is hereby incorporated by reference herein in its entirety.

TECHNICAL FIELD

Embodiments described herein generally relate to pulling a section ofpipe. Selected specific examples relate to removing pipe from theground.

BACKGROUND

Pipe bursting is an existing technique where an old pipe is replaced bybursting the old pipe into the surrounding soil. A new pipe is thenpulled into place where the old burst pipe once was. This technique isdesirable because the old pipe may be replaced without digging a trenchto access it. In some instances it may be desirable to replace an oldpipe trenchlessly, however, it may also be desirable to remove the oldpipe from the ground. One example includes replacement of lead pipes. Itis desirable to replace the pipe trenchlessly to avoid disturbing topsurface structures such as roadways. However it is desirable to removethe lead pipe completely because lead may be hazardous to theenvironment. It may also be desirable to remove other pipe materialsfrom the ground, such as copper or steel, for other reasons that do notinvolve environmental concerns.

Devices and methods are desired to accomplish these and other goals.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a perspective view of selected components of a pipe pullersystem in accordance with some embodiments of the invention.

FIG. 1B is a cross section perspective view of the pipe puller systemfrom FIG. 1A in accordance with some embodiments of the invention.

FIG. 2A is a perspective view of a cable puller in accordance with someembodiments of the invention.

FIG. 2B is a cross section perspective view of the cable puller fromFIG. 2A in accordance with some embodiments of the invention.

FIG. 3A is a side view of a pipe puller system in operation inaccordance with some embodiments of the invention.

FIG. 3B is a top view of a pipe puller system in operation in accordancewith some embodiments of the invention.

FIG. 4A is a pipe loosening device in accordance with some embodimentsof the invention.

FIG. 4B is another pipe loosening device in accordance with someembodiments of the invention.

FIG. 4C is another pipe loosening device in accordance with someembodiments of the invention.

FIG. 4D is a pipe loosening device in use in accordance with someembodiments of the invention.

FIG. 5A is a perspective view of selected components of a pipe pullersystem in accordance with some embodiments of the invention.

FIG. 5B is a cross section perspective view of the pipe puller systemfrom FIG. 5A in accordance with some embodiments of the invention.

FIG. 6A is a side view of a pipe puller system in operation inaccordance with some embodiments of the invention.

FIG. 6B is another side view of a pipe puller system in operation inaccordance with some embodiments of the invention.

FIG. 6C is a top view of a pipe puller system in operation in accordancewith some embodiments of the invention.

FIG. 7 is a flow diagram of a method of pipe extraction in accordancewith some embodiments of the invention.

FIG. 8 is a flow diagram of another method of pipe extraction inaccordance with some embodiments of the invention.

DESCRIPTION OF EMBODIMENTS

The following description and the drawings sufficiently illustratespecific embodiments to enable those skilled in the art to practicethem. Other embodiments may incorporate structural, logical, electrical,process, and other changes. Portions and features of some embodimentsmay be included in, or substituted for, those of other embodiments.Embodiments set forth in the claims encompass all available equivalentsof those claims.

FIG. 1A shows a pulling system 100 coupled to a section of pipe 102according to one example. The pipe 102 is typically buried in theground, and methods and devices described in the present disclosure maybe used to extract the pipe 102 from the ground. It should be noted,however, that the devices and methods for pulling pipe may be used topull pipes in other settings apart from being buried in the ground.

A collar 120 is shown coupled to a proximal end 106 of the pipe 102 inFIG. 1A. A lug 110 is shown coupled to a distal end 104 of the pipe 102.A first cable 112 is coupled to the lug 110, thus coupling the firstcable 112 to the distal end 104 of the pipe 102. A second cable 122 iscoupled to the collar 120, thus coupling the second cable 122 to theproximal end 106 of the pipe 102.

FIG. 1B shows a cross section of the pulling system 100. In the exampleshown, the first cable 112 can be seen passing through an opening in thecollar 120 and passing on to the distal end 104 of the pipe 102. FIG. 1Balso shows two specific examples of coupling the first cable 112 to thedistal end of the pipe 104, and coupling the second cable 122 to theproximal end of the pipe 106.

In the example shown, the first cable 112 is attached to and expander130 using a swage button or a segmented collet type gripping device.When pulled, the expander 130 abuts the lug 110 and applies compressionforce against the distal end 104 of the pipe 102. Further, in theexample shown, the second cable 122 includes a swage button 123 that iscoupled within a swage pocket 126 in the collar 120. When pulled, theswage button 123 applies tension force to the collar 120, and as aresult, to the proximal end 106 of the pipe 102.

In operation, pulling old pipes from the ground can be difficult. Oftenwhen pulling from only the proximal end, the high forces needed toovercome friction with the surrounding soil exceed the tensile strengthof the pipe, and the pipe tears in a middle portion, leaving the distalend still in the ground. Another undesired possibility is when pullingonly from a distal end, the high forces needed to overcome friction withthe surrounding soil exceed a buckle strength of the pipe, and the pipebuckles on itself at the distal end, or within a middle portion stillunderground. As with the scenario of only pulling from the proximal end,this results in an unwanted scenario, where part of the pipe is still inthe ground, and the remaining part will likely have to be excavated inorder to fully remove the old pipe.

Using examples of a pulling system 100 as shown in FIGS. 1A and 1B,extraction force may be applied to more than one location of the pipe.This allows additional extraction force to be exerted without tearing orbuckling the pipe. By attaching at both a proximal end 106, and a distalend 104, the additional extraction force can be applied at the ends thatare easily accessible, without the need for messy or time consumingadhesives along a middle portion of the pipe 102.

Using configurations shown in FIGS. 1A and 1B, an additional advantageis the ability to adjust a force differential between the first cable112 and the second cable 122. For example, the distal end 104 of thepipe 102 may be able to withstand a higher amount of compression forcebefore buckling when compared to a threshold tensile force on theproximal end. In such a case, the first cable 112 (coupled to the distalend 104) may be pulled using a higher force than the second cable 122(coupled to the proximal end 106).

In an additional example, instead of a collar 120 coupled to a proximalend 106, other attachment mechanisms may be used. In one example, a wiremesh gripper (also known informally as a Chinese finger grip) may beused. In one example, a wire mesh gripper is used when pulling leadpipe. Lead pipe is softer than some pipe materials such as steel. In oneexample, a wire mesh gripper provides sufficient grip on a soft materialsuch as lead, and spreads the gripping force over a larger surface area,leading to a lower change of tearing of the lead pipe. In selectexamples, a wire mesh gripper may be used on a proximal end 106 for allpipe materials where sufficient grip may be obtained.

FIGS. 2A and 2B show a cable puller 200 that may be used to power apulling system as described in the present disclosure, such as thepulling system 100 from FIGS. 1A and 1B. FIG. 2A shows a first drum 210coupled to a first drive motor 212, and a second drum 220 coupled to asecond drive motor 222. In one example, the first drum 210 is rotatableseparately from the second drum 220. A drive controller 230 is shown inblock diagram format. The drive controller 230 is coupled to the firstdrive motor 212 and the second drive motor 222 using communication lines232 as illustrated. FIG. 2A shows the first cable 112 from FIGS. 1A and1B spooling onto the first drum 210. Likewise, FIG. 2A shows the secondcable 122 spooling onto the second drum 220. Although two drive motorsare shown, more than two drive motors may be used to increase drivepower if necessary.

In one example, the drive controller 230 is adapted to control the firstdrive motor 212 and the second drive motor 222 to drive the first drumand the second drum at the same time and to adjust a pulling forceindependently for each of the first drum 210 and the second drum 220.Although a pulling force may be independently adjusted, the inventiondoes not require that the pulling forces be different between the twodrums. However, as noted above, it may be advantageous in selectedcircumstances to provide pulling forces that are different from oneanother. FIG. 2A shows the drive controller 230 coupled to the firstdrive motor 212 and the second drive motor 222 through communicationlines 232. In one example, the communication lines 232 are electrical.In one example, the communication lines 232 are hydraulic. Althoughphysical communication lines are shown, the invention is not so limited.In one example, communication with the first drive motor 212 and thesecond drive motor 222 is wireless, through a protocol such as WiFi,Bluetooth, or another suitable communication protocol. In one example,the controller 230 is physically integrated on a frame 201 of the cablepuller 200. In other examples, the controller 230 may be a separateunit, and operate from a physically separate location, while incommunication with the first drive motor 212 and the second drive motor222.

In one example, the first drive motor 212 and the second drive motor 222are hydraulic motors, however the invention is not so limited. Otherexamples of drive motors include electric motors, internal combustiondriven motors, gear reduction driven motors, etc.

FIG. 2B shows additional detail of the cable puller 200 in crosssection. One example of a coupling configuration between cables anddrums is shown. A swage cable end 270 may be inserted in a slot 272within a drum. As shown in FIG. 2B, a pair of swage cable ends 270 maybe used for the pair of cables 112, 122. Although a swage connection iseffective and inexpensive, the invention is not so limited. Otherconnection systems may be used, such as collet type cable grippers,clamps, bolts, etc.

FIG. 2B also shows guide bars 280, 281 that form a close fit againstflanges 211, 221 of the drums 210, 220. In one example, the guide bars280, 281 help ensure that the old pipe spools onto the drums 210, 220and does not spool outside the flanges 211, 221.

A common axle 240 is shown, on which both the first drum 210 and thesecond drum 220 rotate. In the example of FIGS. 2A and 2B, a latch 242is included for optional removal of the axle 240 which may facilitateremoval and/or replacement of one or more of the first drum 210 and thesecond drum 220. In one example, when old pipe is pulled from theground, and wound around one or more of the first drum 210 and thesecond drum 220 it may be desirable to remove a drum that is filled withremoved old pipe, and replace the filled drum with a fresh drum. Thismethod of operation will be described in more detail below. In otherexamples, a filled drum may be spun backwards either under power, ormanually, to remove pipe that has been removed from the ground from oneor more of the drums. In such an example, after removal of the old pipe,additional pipe pulling operations may be performed.

FIG. 2B shows further detail of an example drive system. In FIG. 2B, anfirst drive gear 260 is shown on one side of the first drum 210, and asecond drive gear 250 is shown on one side of the second drum 220. Inone example, the drive gears 250, 260 each engage a correspondingtoothed gear on the first drive motor 212 and the second drive motor222. In one example both drive gears include a number of spaced holes252 or other engaging features. In one example, the drive gears 250, 260may be selectively coupled to the first drum 210 and the second drum 220by placing a pin (not shown) through a selected hole 252. The pin wouldthen drive the drive 250 with the second drum 220 when inserted, andwhen removed, would allow the second drum 220 to rotate freely withrespect to the second drive gear 250. In one example, the first drivegear 260 and the first drum 210 operate in a similar manner.

As noted above, in one example, it may be advantageous to periodicallyremove old pipe from a filled drum in order to continue pullingadditional pipe. One method of removing old pipe from a drum includesremoving a pin or other engaging structure between a drive gear 250, 260and a drum 210, 220 to allow the drum 210, 220 to rotate freely untilthe old pipe has been removed. The pin or other engaging structure maythen be replaced, or re-engaged to continue pulling.

FIGS. 3A and 3B illustrate one method of operation of a pipe pullersystem 300 according to examples of the invention. In FIG. 3A, a pipe tobe replaced 310 is shown buried in the ground 306. An entrance pit 302and an exit pit 304 are dug between the section of pipe to be replaced310. A cable puller 200 is shown located within the exit pit 304. Acollar 320, similar to the collar 120 described in FIGS. 1A and 1B, isshown coupled to a proximal end of the pipe to be replaced 310. A lug310, similar to the lug 110 described in FIGS. 1A and 1B, is also showncoupled to a distal end of the pipe to be replaced 310. Although notshown in FIG. 3A, a first cable and a second cable are coupled to thecollar and lug respectively, as described in examples above.

In the example of FIG. 3A, an expander 312 is also shown coupled to adistal end of the pipe to be replaced 310. In FIG. 3A, a new pipe 314 iscoupled behind the expander 312.

As described in examples above, when using a first and second cable, inconjunction with a collar and lug, extraction force may be applied tomore than one location of the pipe. This allows additional extractionforce to be exerted without tearing or buckling the pipe. As shown inFIG. 3B, after actuating the cable puller 200, the pipe to be replaced310 is pulled from the ground, and spooled around one or more drums ofthe cable puller 200. FIG. 3B illustrates a number of windings 303 ofthe pipe to be replaced 310 as then are spooled on the drum or drums andextracted from the ground 306. In the option shown in FIGS. 3A and 3B,the new pipe 314 is also drawn into the ground at the same time that thepipe to be replaced 310 is removed. The addition of the expander 312further facilitates pulling in the new pipe 314 by expanding thesurrounding soil to make room for the new pipe 314.

FIGS. 4A-4C show an additional tool that may be used in conjunction withpipe puller systems described above to further facilitate removal of oldpipe from the ground. FIG. 4A shows a pipe loosening device 400according to one example. The pipe loosening device 400 includes a solidsingle deforming die 401 and a connection to forcing equipment. In theexample of FIG. 4A, the forcing equipment is a cable 414 that is coupledto the deforming die 401 with a coupler 412. In one example, the cable414 is pulled the cable puller 200, or similar device (not shown). Othercable pulling equipment, such as a cyclic puller, may also be used.

When used, the pipe loosening device 400 or other pipe loosening devicesdescribed below, deforms the pipe to be replaced enough to loosen soilthat surrounds the pipe to be replaced, but the deformation is not largeenough to tear the pipe to be replaced apart. In this way, the pipe tobe replaced maintains enough integrity to be pulled from the groundwithout fracturing, but the loosened soil reduces friction on an outersurface of the pipe to be replaced, facilitating easier removal. Inexample systems and methods using pipe loosening device 400 or otherpipe loosening devices described below, the pipe to be replaced is firstloosened within the soil, then after loosening, a pipe puller system asdescribed in examples of the present disclosure, is used to pull theloosened pipe from the ground.

The solid single deforming die 401 includes a leading end cylinderportion 402 and a trailing end cylinder portion 404. The leading endcylinder portion 402 includes a leading end axis 403, and the trailingend cylinder portion 404 includes a trailing end axis 405. The leadingend axis 403 and the trailing end axis 405 are substantially aligned.

In one example, both the leading end cylinder portion 402 and thetrailing end cylinder portion 404 have a first diameter. In one example,the first diameter substantially matches an inner diameter of a pipe tobe replaced. In one example, the leading end cylinder portion 402 andthe trailing end cylinder portion 404 slide within the pipe to bereplaced with a close tolerance fit. In one example the close tolerancefit serves to guide the solid single deforming die 401 and determineshow a deforming force is applied using a deforming cylinder portion 406.

As noted, the solid single deforming die 401 includes a deformingcylinder portion 406 coupled between the leading end cylinder portion402 and the trailing end cylinder portion 404. The deforming cylinderportion 406 includes an axis 407 that is displaced by a distance 410away from the trailing end axis and the leading end axis. In oneexample, the deforming cylinder portion 406 is coupled between theleading end cylinder portion 402 and the trailing end cylinder portion404 using a gentle transition or slope. In one example, thisconfiguration helps to gradually apply a deforming force to a sidewallof a pipe to be replaced.

In one example, one or more of the leading end cylinder portion 402, thetrailing end cylinder portion 404, and the deforming cylinder portion406 includes a material that is hardened to resist galling or coldwelding on the inside of the pipe to be replaced. In one example, one ormore of the leading end cylinder portion 402, the trailing end cylinderportion 404, and the deforming cylinder portion 406 is formed from ahardened steel. In one example a hardness is within a range of 60-65Rockwell C. In one example, one or more of the leading end cylinderportion 402, the trailing end cylinder portion 404, and the deformingcylinder portion 406 is case hardened, carburized, or otherwise coatedto have a hard external surface.

In one example, a hardened insert is mechanically attached to wearpoints on one or more of the leading end cylinder portion 402, thetrailing end cylinder portion 404, and the deforming cylinder portion406. An example of attachment includes, but is not limited to, screws,bolts, welding, adhesives, dovetail joints etc. Examples of hardenedinserts includes, but is not limited to, tungsten carbide, or othercarbides, hardened tool steel, coated tool steel, etc.

In one example a low friction insert may be used. An example of a lowfriction insert includes, but is not limited to an aluminum-bronzealloy. In the example of aluminum-bronze, such an alloy provides a lowfriction in relation to several pipe material, specifically black iron.In one example, a lubricant may be used to further reduce friction andany resulting galling or cold welding.

FIG. 4B shows another example of a pipe loosening device 420 accordingto one example. The pipe loosening device 420 includes a solid singledeforming die 401 and a connection to forcing equipment. In the exampleof FIG. 4B, the forcing equipment is a drill stem 428 from a directionaldrill. As noted above, in other examples, the pipe loosening device 420may be pulled by a cable.

In the example of FIG. 4B, a threaded connection 422 is shown on theleading end cylinder portion 402. In one example, a second threadedconnection 424 is shown on the trailing end cylinder portion 404.Various combinations of threaded connections may be used in differentcombinations. In the example shown in FIG. 4B, the solid singledeforming die 401 is flexible in the method of connection to forcingequipment. Either pushing or pulling equipment may be used. In theexample, shown, the threaded connections 422, 424 are both femalethreads. However, the invention is not so limited. One or both of thethreaded connections 422, 424 may be male threads instead. In oneexample, one or more of the threaded connections 422, 424 may include atapered thread, to mate with a tapered thread on a directional drillstem.

FIG. 4C shows another pipe loosening device according to one example. Adeforming die 450 is shown that may be used in a manner similar to theexamples shown in FIGS. 4A and 4B. The deforming die 450 includes acylinder portion 452. In one example, the cylinder portion 452 have afirst diameter. In one example, the first diameter substantially matchesan inner diameter of a pipe to be replaced. In one example, the cylinderportion 452 slides within the pipe to be replaced with a close tolerancefit. In one example the close tolerance fit serves to guide thedeforming die 450 and determines how a deforming force is applied usingdeforming inserts as described below.

FIG. 4C shows a first end insert 454, a second end insert 456, and amiddle insert 458. In one example, the inserts 454, 456, 458 includetungsten carbide inserts. Although tungsten carbide is used as anexample, other hard materials may also be used. Examples include, butare not limited to, other carbide materials, hardened tool steels,ceramic materials, etc. Inserts may be secured to the cylinder portion452 in a number of possible configurations, such as welding, or adhesivesuch as epoxy to secure inserts within a pocket. Inserts may also besecured using threaded fasteners through a hole from a side of thecylinder portion 402 opposite the inserts. In one example, the insertsare replaceable.

FIG. 4D shows another example of a pipe loosening device 440 accordingto one example. The pipe loosening device 440 includes a solid singledeforming die 401 and a connection to forcing equipment. The pipeloosening device 440 in FIG. 4C is shown in operation within a pipe tobe replaced 462. The pipe to be replaced is shown embedded within soil461. In operation, the solid single deforming die 401 is pulled orpushed in direction 448. The diameter of the leading end cylinderportion 402 and the trailing end cylinder portion 404 substantiallymatches an inner diameter 446 of the pipe to be replaced 462. Because ofthe substantial matching, the leading end cylinder portion 402 and thetrailing end cylinder portion 404 guide the solid single deforming die401 through the pipe to be replaced 462 in a controlled manner.

As the solid single deforming die 401 is pulled, the deforming cylinderportion 406 is forced against a sidewall of the pipe to be replaced 462.The deforming cylinder portion 406 pushes the sidewall portion outwardinto the surrounding soil and causes a gap 466 to form between thesidewall of the pipe to be replaced 452 and the soil 450. In oneexample, the pipe to be replaced 452 is not burst or in any other waysplit or opened to the soil 461. Bursting, splitting, or otherwiseopening up the pipe to be replaced 462 to the surrounding soil may causeadditional unwanted friction when the pipe to be replaced 462 is laterremoved from the soil along an axis of the pipe. Bursting, splitting, orotherwise opening up the pipe to be replaced 462 may also weaken thepipe to be replaced, and cause it to break during the later extractionoperation where the pipe to be replaced 462 is removed from the soilalong an axis of the pipe.

FIG. 4D shows how the gap 466 increases dimension 444 to a dimensionthat is larger than the diameter 446 of the pipe to be replaced.Although the invention is not so limited, in one example, the diameterof the pipe to be replaced is approximately 1.66 inches, and thedimension 444 after passing of the deforming cylinder portion 406 isapproximately 1.901 inches. In one specific example, for a ⅝ inch copperOD pipe, the dimension 444 is about 13% of the OD. In another specificexample, for a 1½ inch steel OD pipe, the dimension 444 is about 11% ofthe OD. In another specific example, for a 2 inch steel OD pipe, thedimension 444 is about 9% of the OD.

As illustrated in FIG. 4A, in one example, in order to deform, but notburst the pipe to be replaced 462, the deforming cylinder portion 406includes an axis 407 that is displaced by a distance 410 away from thetrailing end axis and the leading end axis that is between 5 and 15percent of the diameter of the leading end cylinder portion 402 and thetrailing end cylinder portion 404. In one example, the displacement 410is approximately 7 percent of the diameter of the leading end cylinderportion 402 and the trailing end cylinder portion 404. In one example,the displacement 410 decreases as the OD of the pipe to be replacedincreases.

As noted above, the diameter of the leading end cylinder portion 402 andthe trailing end cylinder portion 404 will vary depending on the innerdiameter of the pipe to be replaced 462. However, in one example, thepercent displacement of the distance 410 away from the trailing end axisand the leading end axis is proportional, depending on the diameter ofthe pipe to be replaced.

In one example, the passing of the solid single deforming die 401through the pipe to be replaced 462 will loosen the pipe from within thesoil 461. after loosening, the pipe to be replaced 462 may be pulledfrom the ground along an axis of the pipe, such as in direction 448. Ifthe pipe is not loosened from the soil 461, the pipe may tear, withportions of the pipe undesirably remaining in the soil 461.

When using a pipe loosening device (for example devices 400, 420, 450,440) it may be advantageous to hold the pipe in the ground against thedeforming force needed to pull the pipe loosening device through thepipe to be replaced. Although the eventual goal is to remove the pipefrom the ground, it may be advantageous to loosen the whole pipe beforeattempting to extract the pipe from the ground.

FIGS. 5A and 5B illustrate an example of a retainer system 500 is shown.In FIG. 5A, an insert 510 is placed within an inner diameter of a pipeto be replaced 501. FIG. 5B shows a cross section of the insert 510illustrating a portion that is placed inside the inner diameter of apipe to be replaced 501. A clamp 512 is then fastened over an end of thepipe to be replaced 501, such that the clamp 512 grasps the end of thepipe to be replaced 501 between the clamp 512 and the insert 510. Afastener 514, such as one or more bolts, is used to actuate the clamp512. Although a threaded fastener such as bolts are used as an example,any fastener or actuator may be used within the scope of the invention.A central passage 516 is shown within the insert 510 providing access tothe interior of the pipe to be replaced.

In another example, a flare fitting nut may be installed on the pipe tobe replaced 501 and used as a retainer system. Conventional flarefittings provide a configuration where an inner diameter of the pipe tobe replaced is maintained, because no parts are placed within the innerdiameter of the pipe to be replaced. The flared portion of the pipeprovides a structural feature that holds against the flare fitting nut.It may be advantageous to keep an inner diameter of the pipe to bereplaced as large as possible in order to allow a pipe loosening deviceto enter the pipe to be replaced.

In operation, the retainer system 500 may be installed on the pipe to bereplaced at an entrance pit while the pipe is still in the ground. Apipe loosening device (for example devices 400, 420, 450, 440) may thenbe pulled through the central passage 516 in the insert 510, and intothe pipe to be replaced. As the pipe loosening device is pulled, theretainer system 500 may be pulled against the soil and provide areaction force against the soil to keep the pipe to be replaced frompulling into the ground prematurely. The retainer system 500 helpsfacilitate the pulling of the pipe loosening device all the way throughthe pipe to be replaced, thus providing a loosening action along thewhole length of the pipe.

After the pipe is loosened, the retainer system 500 may be removed, andthe pipe to be replaced may be pulled from the ground more easily usingpipe puller systems as described in various examples above.

FIGS. 6A-6C illustrate one example method of pulling pipe from theground using a pipe loosening device as described in examples above. InFIG. 6A, a pipe loosening device 602 is pulled through a pipe to bereplaced 601. In the example shown, a cable puller 200 is used to pullthe pipe loosening device 602, however the invention is not so limited.Other forcing equipment, such as a separate winch, a directional drill,or other pulling or pushing equipment may be used to pull the pipeloosening device 602 through the pipe to be replaced 601. In the exampleshown, a retaining device 500 as described in FIGS. 5A and 5B is firstinstalled to hold the pipe to be replaced 601 in place while the pipeloosening device 602 is pulled.

In FIG. 6B, after loosening the pipe to be replaced 601, a zone ofloosened soil 603 is present around the pipe to be replaced 601. At thisstage, the retaining device 500 is removed, and a collar and lug areinstalled on the pipe to be replaced 601 as described in examples ofpipe puller systems above. Although not shown in FIG. 6B, a first cableand a second cable are coupled to the collar and lug respectively, asdescribed in examples above.

In the example of FIG. 6B, an expander 612 is also shown coupled to adistal end of the pipe to be replaced 601. In FIG. 6B, a new pipe 614 iscoupled behind the expander 612.

As described in examples above, when using a first and second cable, inconjunction with a collar and lug, extraction force may be applied tomore than one location of the pipe. This allows additional extractionforce to be exerted without tearing or buckling the pipe. As shown inFIG. 6C, after actuating the cable puller 200, the pipe to be replaced601 is pulled from the ground, and spooled around one or more drums ofthe cable puller 200. FIG. 6C illustrates a number of windings 603 ofthe pipe to be replaced 601 as then are spooled on the drum or drums andextracted from the ground. In the option shown in FIGS. 6B and 6C, thenew pipe 614 is also drawn into the ground at the same time that thepipe to be replaced 601 is removed.

The zone of loosened soil 603 provided by the operation shown in FIG. 6Areduces a starting friction that must be exceeded to start pulling thepipe to be replaced 601 from the ground. The addition of the expander612 further facilitates pulling in the new pipe 614 by expanding thesurrounding soil to make room for the new pipe 314.

FIG. 7 shows a flow diagram of an example method of pipe extraction. Inoperation 702, a first cable is coupled to a distal end of a pipe buriedin the ground. In operation 704, a second cable is coupled to a proximalend of the pipe. In operation 706, both the first cable and the secondcable are pulled concurrently to extract the pipe from the ground.

FIG. 8 illustrates another flow diagram of an example method of pipeextraction. In operation 802, a deforming die is forced through a pipeto be replaced. In operation 804, at least a portion of a sidewall ofthe pipe is deformed outward into the surrounding soil, but not burst,to compact a local region of the surrounding soil and loosen the pipe.In operation 806, a first cable is coupled to a distal end of the pipe.In operation 808, a second cable is coupled to a proximal end of thepipe. In operation 810, both the first cable and the second cable arepulled concurrently to extract the pipe from the ground.

Any number of possible pipe typed may be replaced using the devices andmethods shown. Examples include, but are not limited to, lead pipes,copper pipes, natural gas pipes, etc. In one particular example, smalldiameter black iron gas pipe may be replaced using the devices andmethods described above. In may be necessary to remove small diameterblack iron gas pipe from the ground, instead of bursting the pipe, dueto concerns for new plastic pipe being drawn in to the ground to replacethe black iron pipe. In some instances, bursting may be inadequate tomove the old pipe out of the way of the new pipe being drawn in. The oldpipe may cut or damage the new pipe. In such an instance, it may bedesirable to remove the old pipe from the ground.

To better illustrate the method and apparatuses disclosed herein, anon-limiting list of examples is provided here:

Example 1 includes a method of pipe extraction. The method includescoupling a first cable to a distal end of a pipe buried in the ground,coupling a second cable to a proximal end of the pipe, and pulling boththe first cable and the second cable concurrently to extract the pipefrom the ground.

Example 2 includes the method of example 1, further including beforecoupling the first cable to the distal end of the pipe, forcing adeforming die through the pipe, and deforming but not bursting at leasta portion of a sidewall of the pipe outward into the surrounding soil tocompact a local region of the surrounding soil and loosen the pipe.

Example 3 includes the method of any one of examples 1-2, furtherincluding adjusting a force differential between the first cable and thesecond cable.

Example 4 includes the method of any one of examples 1-3, whereincoupling the second cable to the proximal end of the pipe includescoupling a collar to the proximal end of the pipe and coupling a thesecond cable to the collar.

Example 5 includes the method of any one of examples 1-4, whereincoupling the first cable to the distal end of the pipe includes routingthe first cable through the collar at the proximal end of the pipe.

Example 6 includes the method of any one of examples 1-5, furtherincluding attaching an expander to the distal end of the pipe.

Example 7 includes the method of any one of examples 1-6, whereinfurther including pulling in a new pipe as the old pipe is removed fromthe ground.

Example 8 includes a cable puller. The cable puller includes a firstdrum coupled to a first drive motor, a second drum coupled to a seconddrive motor, the second drum rotating coaxially with the first drum androtating independently from the first drum, and a drive controlleradapted to control the first drive motor and the second drive motor todrive the first drum and the second drum at the same time and to adjusta pulling force independently for each of the first drum and the seconddrum.

Example 9 includes the cable puller of example 8, wherein the firstdrive motor includes a hydraulic motor.

Example 10 includes the cable puller of any one of examples 8-9, whereinthe second drive motor includes a hydraulic motor.

Example 11 includes the cable puller of any one of examples 8-10,wherein the first drive motor is coupled to the first drum using a geardrive.

Example 12 includes the cable puller of any one of examples 8-11,wherein the second drive motor is coupled to the second drum using agear drive.

Example 13 includes the cable puller of any one of examples 8-12,wherein the first drum and the second drum include swage pockets tocouple to cables.

Example 14 includes the cable puller of any one of examples 8-13,wherein the first drum is wider than the second drum.

Example 15 includes the cable puller of any one of examples 8-13,wherein the first drum is removable and replaceable.

Example 16 includes a pipe puller system. The pipe puller systemincludes a lug to couple to a distal end of a pipe to be removed, acollar to couple to a proximal end of the pipe to be removed, a firstcable to couple to the lug, a second cable to couple to the collar, anda dual cable puller to pull both the first cable and the second cable atthe same time to apply force to the pipe to be removed at both thedistal end and the proximal end at the same time.

Example 17 includes the cable puller system of example 16, wherein thecollar includes an inner sleeve and outer clamp portions.

Example 18 includes the cable puller system of any one of examples16-17, wherein the collar includes a swage pocket to receive the secondcable.

Example 19 includes the cable puller system of any one of examples16-18, wherein the collar includes a passage for the first cable to passthrough.

Example 20 includes the cable puller system of any one of examples16-19, wherein the lug is further coupled to an expander.

Example 21 includes the cable puller system of any one of examples16-20, further including a new pipe coupling located behind theexpander.

The above detailed description includes references to the accompanyingdrawings, which form a part of the detailed description. The drawingsshow, by way of illustration, specific embodiments in which theinvention can be practiced. These embodiments are also referred toherein as “examples.” Such examples can include elements in addition tothose shown or described. However, the present inventors alsocontemplate examples in which only those elements shown or described areprovided. Moreover, the present inventors also contemplate examplesusing any combination or permutation of those elements shown ordescribed (or one or more aspects thereof), either with respect to aparticular example (or one or more aspects thereof), or with respect toother examples (or one or more aspects thereof) shown or describedherein.

In this document, the terms “a” or “an” are used, as is common in patentdocuments, to include one or more than one, independent of any otherinstances or usages of “at least one” or “one or more.” In thisdocument, the term “or” is used to refer to a nonexclusive or, such that“A or B” includes “A but not B,” “B but not A,” and “A and B,” unlessotherwise indicated. In this document, the terms “including” and “inwhich” are used as the plain-English equivalents of the respective terms“comprising” and “wherein.” Also, in the following claims, the terms“including” and “comprising” are open-ended, that is, a system, device,article, composition, formulation, or process that includes elements inaddition to those listed after such a term in a claim are still deemedto fall within the scope of that claim. Moreover, in the followingclaims, the terms “first,” “second,” and “third,” etc. are used merelyas labels, and are not intended to impose numerical requirements ontheir objects.

The above description is intended to be illustrative, and notrestrictive. For example, the above-described examples (or one or moreaspects thereof) may be used in combination with each other. Otherembodiments can be used, such as by one of ordinary skill in the artupon reviewing the above description. The Abstract is provided to complywith 37 C.F.R. § 1.72(b), to allow the reader to quickly ascertain thenature of the technical disclosure. It is submitted with theunderstanding that it will not be used to interpret or limit the scopeor meaning of the claims. Also, in the above Detailed Description,various features may be grouped together to streamline the disclosure.This should not be interpreted as intending that an unclaimed disclosedfeature is essential to any claim. Rather, inventive subject matter maylie in less than all features of a particular disclosed embodiment.Thus, the following claims are hereby incorporated into the DetailedDescription, with each claim standing on its own as a separateembodiment, and it is contemplated that such embodiments can be combinedwith each other in various combinations or permutations. The scope ofthe invention should be determined with reference to the appendedclaims, along with the full scope of equivalents to which such claimsare entitled.

The invention claimed is:
 1. A method of pipe extraction, comprising:coupling a first cable to a distal end of a pipe buried in the ground;coupling a second cable to a proximal end of the pipe; and pulling boththe first cable and the second cable in parallel to extract the pipefrom the ground, wherein a pulling force of on the first cable iscontrolled separately from a pulling force on the second cable.
 2. Themethod of claim 1, further including: before coupling the first cable tothe distal end of the pipe, forcing a deforming die through the pipe;and deforming but not bursting at least a portion of a sidewall of thepipe outward into the surrounding soil to compact a local region of thesurrounding soil and loosen the pipe.
 3. The method of claim 1, furtherincluding adjusting a force differential between the first cable and thesecond cable.
 4. The method of claim 1, wherein coupling the secondcable to the proximal end of the pipe includes coupling a collar to theproximal end of the pipe and coupling the second cable to the collar. 5.The method of claim 4, wherein coupling the first cable to the distalend of the pipe includes routing the first cable through the collar atthe proximal end of the pipe.
 6. The method of claim 1, furtherincluding attaching an expander to the distal end of the pipe.
 7. Themethod of claim 1, further including pulling in a new pipe as the oldpipe is removed from the ground.
 8. A cable puller, comprising: a firstdrum coupled to a first drive motor; a second drum coupled to a seconddrive motor, the second drum rotating coaxially with the first drum androtating independently from the first drum; and a drive controlleradapted to control the first drive motor and the second drive motor todrive the first drum and the second drum at the same time and to adjusta pulling force independently for each of the first drum and the seconddrum, while maintaining a same pulling speed for both the first drum andthe second drum.
 9. The cable puller of claim 8, wherein the first drivemotor includes a hydraulic motor.
 10. The cable puller of claim 8,wherein the second drive motor includes a hydraulic motor.
 11. The cablepuller of claim 8, wherein the first drive motor is coupled to the firstdrum using a gear drive.
 12. The cable puller of claim 8, wherein thesecond drive motor is coupled to the second drum using a gear drive. 13.The cable puller of claim 8, wherein the first drum and the second druminclude swage pockets to couple to cables.
 14. The cable puller of claim8, wherein the first drum is wider than the second drum.
 15. The cablepuller of claim 8, wherein the first drum is removable and replaceable.16. A pipe puller system, comprising: a lug to couple to a distal end ofa pipe to be removed; a collar to couple to a proximal end of the pipeto be removed; a first cable to couple to the lug; a second cable tocouple to the collar; and a dual cable puller to pull both the firstcable and the second cable in parallel to apply force to the pipe to beremoved at both the distal end and the proximal end at the same time,wherein the dual cable puller is configured to control a pulling forceon the first cable separately from a pulling force on the second cable.17. The pipe puller system of claim 16, wherein the collar includes aninner sleeve and outer clamp portions.
 18. The pipe puller system ofclaim 16, wherein the collar includes a swage pocket to receive thesecond cable.
 19. The pipe puller system of claim 16, wherein the collarincludes a passage for the first cable to pass through.
 20. The pipepuller system of claim 16, wherein the lug is further coupled to anexpander.
 21. The pipe puller system of claim 20, further including anew pipe coupling located behind the expander.